From Proto-Semitic *ʿayn-, cognate with Hebrew עַיִן (ʿáyin), Aramaic ܥܝܢܐ (ʿaynā), and Akkadian īnu. The same root gives the letter name ع (ʿayn) in the Arabic alphabet, whose original pictographic shape was drawn as an eye.

عَيْن carries rich cultural weight across the Arab world. Beyond its literal meaning, it is used as a term of endearment — a parent might call a child عَيْنِي ("my eye," i.e., "my precious"). It also sits at the center of the widespread belief in العَيْن (the Evil Eye): an envious glance thought to bring harm, warded off with the phrase ما شاء الله. The word further means a freshwater spring, so place names across the Arab world — like عَيْن شَمْس (Ain Shams) or Al-Ain in the UAE — derive from this secondary sense.